1. Technical Field
The present invention relates to a functional element, an electronic device, an electronic apparatus, and a moving object each using the functional element.
2. Related Art
In recent years, a functional element using, for example, silicon MEMS (Micro Electro Mechanical Systems) technology has been developed as a vibratory device. Further, there has been disclosed a gyro sensor (a capacitive MEMS gyro sensor element) for detecting an angular velocity using a gyro element as an example of the functional element. As an example of such a gyro sensor, there are provided a vibration system structure disposed on an X-Y plane out of the three axes (X axis, Y axis, and Z axis) perpendicular to each other, a substrate for supporting the vibration system structure, a drive device for the vibration system structure, and a detection device for detecting the angular velocity around the Y axis as the gyro sensor disclosed in, for example, JP-A-2012-83112 (Document 1) (see, e.g., Document 1).
In the gyro sensor described in Document 1, there has been used a capacitive MEMS gyro sensor element (hereinafter referred to as a “gyro sensor element”) which has a drive section including an extending section having a frame-like shape, and is provided with a driving spring section disposed outside the extending section, and a detection section and a detecting spring section for connecting the detection section to the extending section both disposed inside the extending section. In this gyro sensor element, the drive section vibrating in the X-axis direction vibrates in the Z-axis direction due to the angular velocity around the Y axis, and the angular velocity can be detected by the detection section detecting the variation in capacitance due to the vibration in the Z-axis direction.
However, in the gyro element described above, a machining error occurs in the dry etching process of the silicon structure constituting the gyro sensor, and thus, the cross-sectional shape, which should normally be a square or a rectangle, is formed to be a parallelogram. Since the cross-sectional shape of the silicon structure becomes a parallelogram as described above, a component (an oblique vibration) vibrating in directions perpendicular to an oblique side of the cross-section occurs in the driving vibration in the drive section vibrating in the X-axis direction. Since the oblique vibration in the drive section has the vibration component in the Z-axis direction, the oblique vibration propagates to the detection section due to a so-called vibration leakage phenomenon, which is a phenomenon that the driving vibration of the drive section propagates to the detection section, and thus, there is caused a so-called quadrature phenomenon that the detection section vibrates in the Z-axis direction as the vibration direction in which the angular velocity is detected. Due to this phenomenon, there are some cases in which the detection section detects the angular velocity despite no angular velocity occurs, or an error occurs in the angular velocity detected. In other words, there is a possibility of degrading the detection accuracy of the angular velocity.